High-precision gravity measurements using absolute and relative

摘要

Accurate detection of time gravity changes attributable to the dynamics ofvolcanoes requires high-precision gravity measurements. With the aim ofimproving the quality of data from the Mount Etna gravity network, weused both absolute and relative gravimeters in a hybrid method. In thisreport, some of the techniques for gravity surveys are reviewed, and theresults related to each method are compared. We show how the totaluncertainty estimated for the gravity measurements performed with thiscombined use of absolute and relative gravimeters is roughly comparableto that calculated when the measurements are acquired using only relativegravimeters (the traditional method). However, the data highlight howthe hybrid approach improves the measurement capabilities for surveyingthe Mount Etna volcanic area. This approach enhances the accuracy ofthe data, and then of the four-dimensional surveying, which minimizesambiguities inherent in the gravity measurements. As a case study, werefer to two gravity datasets acquired in 2005 and 2010 from the westernpart of the Etna volcano, which included five absolute and 13 relativestations of the Etna gravity network.